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  • 1.
    Göktepe, Burak
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. Luleå University of Technology, Sweden.
    Umeki, Kentaro
    Luleå University of Technology, Sweden.
    Hazim, Ammar
    Luleå University of Technology, Sweden.
    Lundström, Staffan
    Luleå University of Technology, Sweden.
    Gebart, Rikard
    Luleå University of Technology, Sweden.
    Soot reduction in an entrained flow gasifier of biomass by active dispersion of fuel particles2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, p. 111-117Article in journal (Refereed)
    Abstract [en]

    Soot is an undesired by-product of entrained flow biomass gasification since it has a detrimental effect on operation of the gasifier, e.g. clogging of flow passages and system components and reduction of efficiency. This study investigated how active flow manipulation by adding synthetic jet (i.e. oscillating flow through orifice) in feeding line affects dispersion of fuel particles and soot formation. Pine sawdust was gasified at the conditions similar to pulverized burner flame, where a flat flame of methane-air sub-stoichiometric mixture supported ignition of fuel particles. A synthetic jet flow was supplied by an actuator assembly and was directed perpendicular to a vertical tube leading to the center of the flat flame burner through which pine sawdust with a size range of 63-112. μm were fed into a reactor. Quartz filter sampling and the laser extinction methods were employed to measure total soot yield and soot volume fraction, respectively. The synthetic jet actuator modulated the dispersion of the pine sawdust and broke up particle aggregates in both hot and cold gas flows through generation of large scale vortex structures in the flow. The soot yield significantly reduced from 1.52. wt.% to 0.3. wt.% when synthetic jet actuator was applied. The results indicated that the current method suppressed inception of young soot particles. The method has high potential because soot can be reduced without changing major operation parameters. © 2016.

  • 2.
    Han, Tong
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sophonrat, Nanta
    KTH Royal Institute of Technology, Sweden.
    Tagami, Ayumu
    KTH Royal Institute of Technology, Sweden ; Nippon Paper Industries Co., Japan.
    Sevastyanova, Olena
    KTH Royal Institute of Technology, Sweden.
    Mellin, Pelle
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Characterization of lignin at pre-pyrolysis temperature to investigate its melting problem2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 235, p. 1061-1069Article in journal (Refereed)
    Abstract [en]

    Technical lignin particles melt under relatively low temperature. This results in the problem in the continuous feeding and fluidization during lignin pyrolysis, which in turn limits its utilization on a large scale. In this study, two most available types of lignin have been used to investigate the lignin melting problem, which are Kraft lignin (KL) from pulping process and hydrolysis lignin (HL) from bio-ethanol production process. Elemental composition, thermal property and thermally decomposed derivatives of each sample are tested by elemental analyzer, TGA, DSC, and Py-GC/MS. Morphology, structure and crystal change before and after heat treatment are tested by microscopy, FTIR and XRD. All results suggest that lignin structure determines its melting properties. Kraft lignin from pulping process contains a less cross-linked structure. It melts under heating. On the other hand, hydrolysis lignin from hydrolysis process contains a highly crossed-linked and condensed structure. It does not melt before decomposition under heat treatment. Modifying lignin structure is suggested for the resolution of technical lignin melting problem.

  • 3.
    Holmgren, Per
    et al.
    Umeå University, Sweden.
    Wagner, David R.
    Umeå University, Sweden.
    Strandberg, Anna
    Umeå University, Sweden.
    Molinder, Roger
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Umeki, Kentaur
    Luleå University of Technology, Sweden.
    Broström, Markus
    Umeå University, Sweden.
    Size, shape, and density changes of biomass particles during rapid devolatilization2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 206, p. 342-351Article in journal (Refereed)
    Abstract [en]

    Particle properties such as size, shape and density play significant roles on particle flow and flame propagation in pulverized fuel combustion and gasification. A drop tube furnace allows for experiments at high heating rates similar to those found in large-scale appliances, and was used in this study to carry out experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion. The objective of this study was to develop a particle conversion model based on optical information on particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved to three narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized using optical methods. Different shape descriptors were evaluated and a shape descriptor based on particle perimeter was found to give significant information for accurate estimation of particle volume. The optical conversion model developed was proven useful and showed good agreement with conversion measured using a reference method based on chemical analysis of non-volatilized ash forming elements. The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoring of particle conversion, provided density data has been calibrated.

  • 4.
    Ji, Jie
    et al.
    University of Science and Technology of China, China.
    Fan, Chuan Gang
    RISE, SP – Sveriges Tekniska Forskningsinstitut. University of Science and Technology of China, China.
    Li, Ying Zhen
    Ingason, Haukur
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Sun, Jin Hua
    University of Science and Technology of China, China.
    Experimental study of non-monotonous sidewall effect on flame characteristics and burning rate of n-heptane pool fires2015In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 145, p. 228-233Article in journal (Refereed)
    Abstract [en]

    To study the influence of sidewall effect on flame characteristics and burning rate, a series of experiments with heptane pools was conducted. The results showed that as the fires were placed close to the sidewall, the flames inclined to the sidewall due to the restriction on air entrainment, and the burning rate increased on the whole, which could be mainly due to the enhanced radiation from the heated sidewall and ceiling flame. However, regardless of fuel pool shape, the burning rate obtained the peak value when the fire was near the sidewall, rather than attached to the sidewall, resulting from less flame radiation from the vertical flame part to the fuel in the latter case. The ratio of longitudinal ceiling flame length to transverse length tended to decrease with the fire moving close to the sidewall. For cases with the largest length and wall fires, the ratio was nearly 0.5, which could be explained according to the theory of mirror effect. Also, due to the non-monotonous sidewall effect, a higher burning rate did not necessarily lead to a larger ceiling flame length.

  • 5.
    Jones, Frida
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Förbrännings- och aerosolteknik.
    Bankiewicz, Dorota
    Hupa, Mikko
    Occurrence and sources of zinc in fuels2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 117, no A, p. 763-775Article in journal (Refereed)
  • 6.
    Lu, Xiaohu
    et al.
    Nynas AB, Sweden.
    Sjövall, Peter
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Soenen, Hilde
    Nynas NV, Belgium.
    Andersson, Martin
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Microstructures of bitumen observed by environmental scanning electron microscopy (ESEM) and chemical analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS)2018In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 229, p. 198-208Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to characterize structures induced on bitumen surfaces under analysis by environmental scanning electron microscopy (ESEM), and to examine possible contributing factors to the formation of their formation. Various bitumen samples are investigated, including soft and hard, as well as polymer modified bitumen. Chemical characterization is carried out by time-of-flight secondary ion mass spectrometry (TOF-SIMS), combined with principle component analysis (PCA). The study shows that, for soft bitumen, a tube pattern or worm structure is rapidly formed during ESEM analysis, but for hard bitumen, a longer exposure time is needed to develop a structure. The structures on the hard bitumen are also denser as compared to those on the soft bitumen. When sample specimens are deformed or stretched, the orientation of the created deformation is clearly reflected in the structures formed under ESEM, and for soft bitumen, the structure disappears overnight in vacuum but reappears with the same pattern upon repeated ESEM analysis. TOF-SIMS shows small but consistent chemical differences, indicating higher aliphatic and lower aromatic contents on the surface of the structured area compared to the unstructured area. Based on an estimated temperature increase on the bitumen surface due to the electron-beam irradiation, it is speculated that the ESEM-induced worm structure may be attributed to evaporation of volatiles, surface hardening and local expansion. In addition, under the electron-beam exposure, certain chemical reactions (e.g. breaking of chemical bonds, chain scission and crosslinking) may take place, possibly resulting in the observed chemical differences between the structured and unstructured areas.

  • 7.
    Lu, Xiauhu
    et al.
    Nynas AB, Sweden.
    Sjövall, Peter
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Soenen, Hilde
    Nynas NV, Belgium.
    Structural and chemical analysis of bitumen using time-of-flight secondary ion mass spectrometry (TOF-SIMS)2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 199, p. 206-218Article in journal (Refereed)
    Abstract [en]

    The chemical composition and structures of bitumen surfaces are characterised using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The effect of wax is considered by comparing a wax-free bitumen with a bitumen that contains natural wax and a wax-free bitumen to which a small amount of wax has been added. The results demonstrate that TOF-SIMS is a powerful method for the chemical characterisation of surface structures and phase segregation phenomena in bitumen. It is evident that the structures formed on the bitumen surface are closely related to the wax content and that these structures, as well as the surface in general, are enriched in wax-related compounds (aliphatic hydrocarbons with a high degree of saturation). For the wax-free bitumen, the surface is characterised by a homogeneous distribution without chemical variations or phase structures and by a stronger signal intensity from aromatic compounds. When adding wax to the wax-free bitumen, extensive wax segregation occurs, but differently from the natural waxy bitumen, no bee structures are observed. Furthermore, fracture surfaces of all the wax-containing samples reveal circular structures, which are distinctly different from those observed on the original surfaces. The obtained chemical knowledge on bitumen surfaces and phase structures is of fundamental importance to understand performance differences of this type of materials.

  • 8.
    Marklund, Magnus
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Tegman, R.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    CFD modelling of black liquor gasification: Identification of important model parameters2007In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 86, no 42351, p. 1918-1926Article in journal (Refereed)
    Abstract [en]

    Pressurized high temperature black liquor gasification has the potential to significantly improve the efficiency of energy and chemical recovery in the pulping industry and to enable new processes, e.g. production of renewable automotive fuels from the formed synthesis gas. However, the current process is still considered as novel and the interest in validated computer models for scale-up and process optimisation is large. In this paper a sensitivity analysis on the four most important model parameters in the pre-processing 'droplet composition model' for a proposed CFD model has been performed. It was shown that careful measurements of the amount of sulphur released to the gas phase as H2S during devolatilization and the concentration ratio of Na2S and Na2SO4 in the black liquor char under real process conditions are of great importance for calibration of the model. © 2007 Elsevier Ltd. All rights reserved.

  • 9. Paulrud, S.
    et al.
    Nilsson, C.
    Ohman, M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Reed canary-grass ash composition and its melting behaviour during combustion2001In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 80, no 10, p. 1391-1398Article in journal (Refereed)
    Abstract [en]

    Spring harvested reed canary-grass (RCG) with various chemical compositions was combusted in a 180 kW boiler. The ash melting behaviour was studied and the ash was analysed. Estimation of melting behaviour was done by ASTM fusion test, a bench-scale fluidized-bed combustion test (5 kW), and by extracting melting behaviours from the ternary phase diagram SiO2-CaO-K2O. The initial melting temperatures seem to be similar for the different samples; however, for low ash content (3-4% DM) higher portions of melt occurred in the lower temperature range <1200°C and for high ash content fuels (5-10%) more melting occurred in a higher temperature range, >1500°C. © 2001 Elsevier Science Ltd. All rights reserved.

  • 10. Risberg, M.
    et al.
    Öhrman, Olov .G.W
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Nilsson, P.T.
    Gudmundsson, A.
    Sanati, M.
    Influence from fuel type on the performance of an air-blown cyclone gasifier2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 116, p. 751-759Article in journal (Refereed)
    Abstract [en]

    Entrained flow gasification of biomass using the cyclone principle has been proposed in combination with a gas engine as a method for combined heat and power production in small to medium scale (<20 MW). This type of gasifier also has the potential to operate using ash rich fuels since the reactor temperature is lower than the ash melting temperature and the ash can be separated after being collected at the bottom of the cyclone. The purpose of this work was to assess the fuel flexibility of cyclone gasification by performing tests with five different types of fuels; torrefied spruce, peat, rice husk, bark and wood. All of the fuels were dried to below 15% moisture content and milled to a powder with a maximum particle size of around 1 mm. The experiments were carried out in a 500 kWth pilot gasifier with a 3-step gas cleaning process consisting of a multi-cyclone for removal of coarse particles, a bio-scrubber for tar removal and a wet electrostatic precipitator for removal of fine particles and droplets from the oil scrubber (aerosols). The lower heating value (LHV) of the clean producer gas was 4.09, 4.54, 4.84 and 4.57 MJ/Nm3 for peat, rice husk, bark and wood, respectively, at a fuel load of 400 kW and an equivalence ratio of 0.27. Torrefied fuel was gasified at an equivalence ratio of 0.2 which resulted in a LHV of 5.75 MJ/Nm3 which can be compared to 5.50 MJ/Nm3 for wood powder that was gasified at the same equivalence ratio. A particle sampling system was designed in order to collect ultrafine particles upstream and downstream the gasifier cleaning device. The results revealed that the gas cleaning successfully removed >99.9% of the particulate matter smaller than 1 μm. © 2013 Elsevier Ltd. All rights reserved.

  • 11.
    Sedlmayer, Irene
    et al.
    Vienna University of Technology, Austria; BIOENERGY 2020+ GmbH, Germany.
    Arshadi, Mehrdad
    SLU Swedish University of Agricultural Sciences, Sweden.
    Haslinger, Walter
    BIOENERGY 2020+ GmbH, Germany; Luleå University of Technology, Sweden.
    Hofbauer, Hermann
    Vienna university of Technology, Austria.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Lönnermark, Anders
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Nilsson, Calle
    SLU Swedish University of Agricultural Sciences, Sweden.
    Pollex, Annett
    DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Germany.
    Schmidl, Christoph
    BIOENERGY 2020+ GmbH, Germany.
    Stelte, Wolfgang
    DTU Technical University of Denmark, Denmark.
    Wopienka, Elisabeth
    BIOENERGY 2020+ GmbH, Germany.
    Bauer-Emhofer, Waltraud
    BIOENERGY 2020+ GmbH, Germany; Vienna University of Technology, Austria.
    Determination of off-gassing and self-heating potential of wood pellets – Method comparison and correlation analysis2018In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 234, p. 894-903Article in journal (Refereed)
    Abstract [en]

    Several methods for identifying the phenomena of self-heating and off-gassing during production, transportation and storage of wood pellets have been developed in recent years. Research focused on the exploration of the underlying mechanisms, influencing factors or the quantification of self-heating or off-gassing tendencies. The present study aims at identifying a clear correlation between self-heating and off-gassing. Thus, different methods for determining self-heating and off-gassing potentials of wood pellets are compared. Therefore, eleven wood pellet batches from the European market were analyzed. For this investigation, three methods for the determination of self-heating, like isothermal calorimetry, oxi-press and thermogravimetric analysis, and four methods for off-gassing, like volatile organic compound (VOC) emissions measurements, gas phase analysis of stored pellets in a closed container by offline and by glass flask method and determination of fatty and resin acids content, were performed. Results were ranked according to the self-heating and off-gassing tendency providing a common overview of the analyzed pellets batches. Relations between different methods were investigated by Spearman's correlation coefficient. Evaluation of the results revealed an equal suitability of offline and glass flask methods to predict off-gassing tendency and indicated a very significant correlation with isothermal calorimetry for the identification of self-heating tendency. The thermogravimetric analysis as well as the fatty and resin acids determination proved to be insufficient for the exclusive assessment of self-heating and off-gassing tendency, respectively.

  • 12.
    Sjövall, Peter
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Pomerantz, Andrew E.
    Schlumberger-Doll Research, USA.
    Lu, Xiaohu
    Nynäs AB, Sweden.
    Mullins, Oliver C.
    Schlumberger-Doll Research, USA.
    Time of flight-secondary ion mass spectrometry (TOF-SIMS) study of diverse asphaltenes2018In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 220, p. 638-644Article in journal (Refereed)
    Abstract [en]

    Mass spectrometry has been used to elucidate a large variety of properties of asphaltenes. Here, time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to probe three diverse asphaltene types with wide ranging fractions of alkyl carbon to the sum of alkyl plus aromatic carbon (Rc), immature source rock asphaltenes (ISA with Rc ∼ 0.75); petroleum asphaltenes (PA with Rc ∼ 0.5); and coal-derived asphaltenes (CDA with Rc ∼ 0.25). In addition, the asphaltenes from a commercial bitumen are examined. Primary ion surface bombardment using the Bi3 + ion yields high energy density of deposition and significant molecular fragmentation with secondary ion formation. Formation of free radical cation fragments is generally suppressed especially for smaller fragments except for specific cases. Possible structures, especially cations of common aromatic compounds, are suggested for fragments with relatively large cross section of formation. Principal component analysis of the fragmentograms allows identification of key properties of the complex fragmentation patterns for the different samples. Comparisons of TOF-SIMS fragmentograms show a fundamental difference for small fragments between CDAs and all petroleum derived asphaltenes with CDAs being dominated by aromatic carbon fragments whereas all petroleum derived asphaltenes show a large fraction of fragments from alkyl carbon. However, the type of alkyl carbon fragments did not exhibit systematic trends with Rc, nor with the extent of chemical reaction or chemical processing of the materials. Consequently, it appears that having an appreciable alkane fraction is a basic property of petroleum derived asphaltenes, but the exact type of alkane carbon for differing samples of these asphaltenes is more idiosyncratic than systematic. 

  • 13.
    Strömberg, Niklas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Biodiesel degradation rate after refueling2013In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 105, no Mar, p. 301-305Article in journal (Refereed)
  • 14.
    Strömberg, Niklas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Eriksson, H.
    Scania, Sweden.
    Saramat, A.
    Scania, Sweden.
    Determination of phase separation efficiency for biodiesel quality and blending2014In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 117, no pt A, p. 74-78Article in journal (Refereed)
    Abstract [en]

    In this study we reintroduce phase separation efficiency as an important characteristic for biodiesel quality and blending. The ability of the fuel to emulsify water is possibly one of the most important features behind biological and chemical fuel degradation but yet, no methods that directly measure this property are included in the standard biodiesel regulation EN14214. The proposed simple technique for fuel quality testing is based on the time it takes for ultra-purified water to become transparent after complete mixing with an equal volume of fuel, measured by kinetic absorbance spectrophotometry. In this study we screen the phase separation efficiency (measured as separation time) of purified, un-aged and aged Fatty Acid Methyl Esters (FAME/B100) and its blends with EN590 with 7% FAME without detergents (B7 reference fuel Euro VI Part no 546061-35 and B100) as well as for FAME blends with a commercial EN590. The B7 fuel was used as reference in all measurements. Aged biodiesel (FAME/B100) almost doubled (1.8 times) its separation time compared to the un-aged FAME/B100 sample and had almost three times (2.9) longer phase separationtime relative the reference B7 fuel. Also fuel blends showed long separation times. A fuel blend based on aged FAME/B100 blended with B7 to a corresponding B30 (30% FAME) gave after three consecutive 10 s mixings stable emulsions (>30 min) in two out of three replicates. All fuels blended with commercial EN590 showed excellent phase separation efficiencies with significantly shorter separation times than FAME/B100. We also show that the phase separation efficiency of the B30 blend could be improved after the rape seed ester was vacuum distilled before blending with B7 petrodiesel. The results indicate that likely emulsion problems associated with the B30 blends can be circumvented with proper selection of compatible petroleum components as well as FAME purifications.

  • 15.
    Strömberg, Niklas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Sahlin, Eskil
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Oorganisk kemi (Kmoo).
    Determination of the short-chain fatty acid pattern in biodiesel using high throughput syringe solvent extraction and ion exclusion chromatography2012In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 97, p. 531-535Article in journal (Refereed)
  • 16.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Brackmann, Christian
    Lund University, Sweden.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Mannazhi, Manu
    Lund University, Sweden.
    Simonsson, Johan
    Lund University, Sweden.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Bengtsson, Per Erik
    Lund University, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 252, p. 125-134Article in journal (Refereed)
    Abstract [en]

    The objective of this work was to move towards developing a comprehensible Computational Fluid Dynamics (CFD) model to facilitate the predictive modeling of Fast Pyrolysis Oil (FPO) spray combustion. A CFD model was implemented from the literature and results were compared to 2D data from non-intrusive optical diagnostics involving Planar Laser Induced Fluorescence of the OH radical, Mie scattering imaging and two-color pyrometry using a laboratory-scale, CH 4 /air flat-flame with an air-assist atomizer. Furthermore, flame radiation and contributions from graybody sources, chemiluminescence and soot were studied experimentally using emission spectroscopy and Laser Induced Incandescence (LII). Reasonable qualitative agreement was found between experimental and model results in terms of flame structure and temperature. Emission spectroscopy and LII results revealed and confirmed earlier observations regarding the low soot concentration of FPO spray flames; furthermore, it was shown that a significant portion of flame radiation originated from graybody char radiation and chemiluminescence from the Na-content of the FPO. These suggest that the treatment of soot formation might not be important in future computational models; however, the description of char formation and Na chemiluminescence will be important for accurately predicting temperature and radiation profiles, important from the point of e.g., large-scale power applications. Confirmed low soot concentrations are promising from an environmental point of view.

  • 17.
    Toth, Pal
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center. University of Miskolc, Hungary.
    Ögren, Yngve
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Sepman, Alexey
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Vikström, Therese
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Gren, Per
    Luleå University of Technology, Sweden.
    Wiinikka, Henrik
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Spray combustion of biomass fast pyrolysis oil: Experiments and modeling2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 237, p. 580-591Article in journal (Refereed)
    Abstract [en]

    In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime. 

  • 18.
    Wallqvist, Viveca
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Adhesive surface characteristics of bitumen binders investigated by Atomic Force Microscopy2013In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 113, p. 248-256Article in journal (Refereed)
  • 19.
    Wiinikka, Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Boman, Christoffer
    Bostrom, D.
    Ohman, M.
    Influence of fuel ash composition on high temperature aerosol formation in fixed bed combustion of woody biomass pellets2007In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 86, p. 181-193Article in journal (Refereed)
    Abstract [en]

    In this work, the influence of fuel ash composition on high temperature aerosol formation during fixed bed combustion of woody biomass (two wood pellets and one bark pellets) were investigated experimentally in a laboratory reactor and theoretically through chemical equilibrium model calculations. For all fuels, the particle mass size distribution in the PM2.5 region was bimodal, with one fine mode and one coarse mode. Early in the flame, the fine mode was dominated by particles from incomplete combustion and these particles were rapidly oxidised in the post flame zone. After the hot flame, the fine mode concentration and the particle diameter increases gradually when the temperature decreases due to condensation of vaporised inorganic matter, K, Na, S, Cl, and Zn. For two of the fuels also P could be found in the fine particles. The coarse mode consisted of carbon, refractory metals and considerable amount of alkali. Further, the initial fuel alkali concentration and the alkali to silicon ratio (K + Na)/Si influenced the amount of vaporised aerosol forming alkali matter. Finally, the present study shows that, combustion temperature and fuel ash composition is of major importance for the formation of high temperature aerosols in fixed bed combustion of woody biomass pellets. © 2006 Elsevier Ltd. All rights reserved.

  • 20.
    Wiinikka, Henrik
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Johansson, Ann-Christine
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Sandström, Linda
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Öhrman, Olov G.W.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Fate of inorganic elements during fast pyrolysis of biomass in a cyclone reactor2017In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 203, p. 537-547Article in journal (Refereed)
    Abstract [en]

    In order to reduce ash related operational problem and particle emissions during pyrolysis oil combustion it is important to produce pyrolysis oil with very low concentration of inorganics. In this paper, the distribution of all major inorganic elements (S, Si, Al, Ca, Fe, K, Mg, Mn, Na, P, Ti and Zn) in the pyrolysis products (solid residue and two fractions of pyrolysis oil) was investigated during pyrolysis of stem wood, bark, forest residue, salix and reed canary grass. The raw materials were pyrolysed in a cyclone reactor and the produced pyrolysis oils were recovered as two oil fractions, a condensed fraction and an aerosol fraction. The inorganic composition of the ingoing raw material, the solid residue and the two pyrolysis oil fractions were analysed with inductively coupled plasma spectrometry techniques. All major inorganic elements, except sulphur, were concentrated in the solid residue. A significant amount of sulphur was released to the gas phase during pyrolysis. For zinc, potassium and iron about 1–10 wt% of the ingoing amount, depending on the raw material, was found in the pyrolysis oil. For the rest of the inorganics, generally less than 1 wt% of the ingoing amount was found in the pyrolysis oil. There were also differences in distribution of inorganics between the condensed and the aerosol oil fractions. The easily volatilized inorganic elements such as sulphur and potassium were found to a larger extent in the aerosol fraction, whereas the refractory elements were found to a larger extent in the condensed fraction. This implies that oil fractionation can be a method to produce oil fractions with different inorganic concentrations which thereafter can be used in different technical applications depending on their demand on the inorganic composition of the pyrolysis oil.

  • 21.
    Öhrman, Olov .G.W
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Häggström, C.
    Wiinikka, Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Hedlund, J.
    Gebart, Rikard
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energy Technology Center.
    Analysis of trace components in synthesis gas generated by black liquor gasification2012In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 102, p. 173-179Article in journal (Refereed)
    Abstract [en]

    The only pressurized black liquor gasifier currently in operation is located in Sweden. The composition of the main components in the gas has been reported previously. The main components are H 2, CO, CO 2, N 2, CH 4, and H 2S. In the present work, trace components in the gas have been characterized and the results are hereby reported for the first time. Samples were taken at two occasions during a one year period. The benzene concentration in the gas varied only slightly and the average concentration was 158 ppm. Benzene is formed by thermal cracking of the biomass. The COS concentration varied substantially and the average concentration was 47 ppm. The variations may be related to how the quench is operated. A few ppm of C 2-hydrocarbons were also observed in the gas and the variation was probably a result of varying oxygen to black liquor ratio. No tars were observed in the gas. However, tar compounds, such as phenanthrene, pyrene, fluoranthene and fluorene were detected in deposits found on the pipe walls after the gas cooler. The concentration of particles in the synthesis gas was very low; <0.1 mg/N m 3, which is comparable to the particulate matter in ambient air. Submicron particles were comprised of elements such as C, O, Na, Si, S, Cl, K, and Ca, and these particles probably originated from the black liquor. Larger particles were comprised mainly of Fe, S and Ni and these particles probably resulted from corrosion of steel in the plant pipe-work. In summary, the concentrations of trace components and particles in the gas are quite low. © 2012 Elsevier Ltd. All rights reserved.

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